Questions about "balanced stacks" and spools

[zeke79]

I finally picked open a Schlage core with spool pins, and it's left me with some questions.

(Thank you le.nutzman for this post: Re: help with a master lock spool pins? it helped me immensely)

http://i548.photobucket.com/albums/ii33 ... ernals.jpg

Behavior of spools when picking

This was the most interesting lock I've played with yet. I have a Master 140, which supposedly has security pins, but I can't really feel them. (Ironically, I opened it within five minutes of trying, and several times since, but these were dumb luck, and not a dependably repeatable event) When the Master 140 has opened, I haven't gotten nearly the feedback I got with this lock. However, here each pin in this lock did the "...over exagerated forward movement of the plug .... counter rotation ...l lurch forward moderately" described by le.nutzman.

The examples of spools in action I have seen show a single pin in action only. In order to get that large "10 degree open" wouldn't all the other pins either need to be picked or also at the narrow part of the spool? I've been trying to visualize what's going on inside the lock and hope someone can tell me if the procedure I have in mind is correct:

1. Pick all pins in the lock which are not already set to either the set position (regular pins) or to the "narrow" part of the spool.
2. When the last unset pin is lifted, the 10 degree open" occurs. All unset pins are now spools
3. Find the tightest spool, and pick it above the shear line. The "backwards creep and surge" should occur as it sets.
4. While setting the tightest spool, normal pins may drop, so be prepared to pick them again
5. Repeat until lock opens. (The normal pins may be the last to set)

Is this what was going on?

Balanced Stacks?

I've been wondering if it would be possible to decode a lock by measuring via a thin probe the amount each pin can be raised before it "bottoms out" by fully compressing the spring. Searching around, I found some mentions of "balanced stacks" but no further information. Looking at the springs here, it seems there are shorter springs on matched with the longer pins, and vice versa. Are these "balanced stacks" and am I correct in assuming they are intended to prevent the type of attack I described?

Colored pins? Evidence of repinning?

The two shorter pins (1 and 3) seem to be colored. I've seen a DIY repinning kit at Home Depot which has colored pins. Is the presence of these colored pins evidence that someone (locksmith or otherwise) repinned this lock in the field?

Sorry for all the questions, I'm quite intrigued.

[TOWCH]

It's possible, but the path of least resistence on any lock vulnerable to such an attack is bumping. Might be a good decoder to hide against bumping forensics.

Decoding could either be accomplished via a wire decoder that uses a bracket to guide 5 or 6 wires at correct spacing, that can clamp the wires either individually or all at once. All at once would be easier.

The alternative would be a set of depth cut, single stack, "comb picks." If the comb pick bottoms out without being able to touch the top of the keyway while parallel with the keyway: move to the next one until you bottom out.

I would imagine the color coded pins are from a rekeying kit. Some locks can be decoded visually based on these color coded pins.

Good post btw. Well organized and easy to read.

[TOWCH]

On that lock, simply picking the first pin, and raking the last four with moderate tension should set all of the spools.

The most rotation possible is to pick every pin except for the spool that allows the most rotation, but I doubt the difference between spools is noticible even if it is slightly mechanically exagerated.

[Squelchtone]

TOWCH is right, very good post.

I was looking at the springs, especially #4, and I don't think that someone put different sized springs in that lock to balance the stacks. The condition of the lock suggests years of use and I believe those springs have become compressed over time and retained that shape/length when removed from the lock.

The pins I have seen in Medeco and ASSA Twin locks use all the same springs, but they use different sized top pins to balance the stack against the aforementioned attack. They even have 2 different sized mushroom pins in Medeco, I believe the #3 and #5 size to stop decoding and help stop picking attempts.

Squelchtone

[Squelchtone]

tballard: here's a good post regarding this topic:

http://www.lockpicking101.com/viewtopic.php?f=9&t=33801&start=0

[tballard]

Thanks for the kind words and great answers!

squelchtone: I think you're absolutely right about the spring compression over time. These are locks I pulled from my local ReStore, and in some cases selected because I thought well-worn locks might provide some interesting characteristics I couldn't buy in a store. I counted the coils of the springs this morning, and they all have the same number, so unless someone got extremely fancy with different gauge spring wire, compression is the obvious answer. (Why I didn't think to count them before is a head-slapper though) Thanks for the link to that post. Very interesting. I hadn't found that one in my searches.

TOWCH: I've actually got an idea for building a decoder which maybe I'll get motivated and try. I suppose I should go look up comb picks and related tools first before discussing it more though. (I think comb picks may be advanced, and I don't want to naively re-invent something and get in trouble with the mods....) At this point I'm focusing on SPP rather than raking and bumping, because I think I'm learning more from it. I don't have anything against other methods, I just think at my success in raking is more due to crappy locks and luck than skill presently.

One last question, a bit off topic: I sized that image down, but obviously not enough. Is there a guideline to what the maximum inline image size should be? I went for 1024 px wide and under 100 Kb, but seemed to have misjudged. Perhaps the authoratative answer could be added this to the FAQ under FAQ: Forum Usage/Posting images?